Unraveling structure-driven astringency perception of polyphenols and elucidating multimodal mitigation mechanism by citrus pectin

Dietary polyphenols offer several potential health benefits, but their interactions with mucin in human saliva leads to astringency, which reduces the palatability of polyphenol-enriched beverages. The structure-dependent mechanisms of polyphenol-induced astringency are still poorly understood. Moreover, there is a lack of knowledge of the pathways by which pectin molecules can mitigate polyphenol astringency. This study used multiscale analytical and computational tools to elucidate the astringency mechanisms of different polyphenols (caffeic acid, chlorogenic acid, naringin, and rutin), and the origin of citrus pectin reducing astringency. E-tongue analysis confirmed flavonoid-induced astringency more pronounced than phenolic acids, indicating a structure-dependent effect. Spectroscopic analysis indicated that hydrophobic interactions were mainly responsible for the astringency of phenolic acids and naringin, whereas a combination of hydrophobic interactions and hydrogen bonding was responsible for that of rutin. Citrus pectin (0.1-0.3%) was found to reduce the astringency by around 16-45%, with greater efficacy against flavonoid-induced astringency, highlighting important structural differences. Citrus pectin mainly reduced astringency by competitively binding polyphenols, forming ternary complexes, enhancing homogeneity, and forming a cross-linked (naringin) or a flake-like coverage (phenolic acids/rutin). These findings provide new insights into the role of polyphenols and pectin on astringency, which may promote the development of polyphenol-rich beverages with enhanced palatability.